Current wireless sensor approaches include miniature sensor nodes and a receiving station. The receiving station receives data from the sensor nodes and processes the data and/or forwards the data to a central collection station.
To date, the miniature sensor nodes are typically manufactured as a single, integrated unit. For example, a node may be configured as a strain sensor, a temperature sensor, an accelerometer sensor, or the like. When a different type of sensor is required, a new sensor node must be designed and manufactured. Even when two different sensor nodes incorporate overlapping functionality, one sensor node cannot be reconfigured to perform as an alternative type of sensor node. One approach offers a sensor research development platform that enables some flexibility when testing and developing new sensor nodes. However, the platform is much larger than a typical sensor node and is neither intended for nor optimized for actual implementations.
Similarly, the sensor nodes also are designed for a particular power source, and therefore cannot readily change from one type of power source to another. As a result, different sensor nodes must be designed to include a particular power source that is conducive for different application environments (e.g., sunny, outdoor environment versus in a warehouse), which may require the same sensing capability. In modern computing devices, the manufacturing trend is also towards integration of numerous functions into a single component. For example, a motherboard for a modern personal computer includes several functions, such as video, I/O ports, etc., which were previously included on separate microcomputers.
Further, power consumption is frequently a limiting factor in the sampling and transmission rates for current sensor nodes. In general, higher sampling and/or transmission rates require additional power consumption. Because of the limited amount of available power in current sensor nodes, sampling and transmission rates are typically very low. The transmission rate is also limited by the type of network in which sensor nodes are deployed. In particular, most multiple sensor node networks are mesh networks, which generally cannot effectively use more than approximately twenty percent of their nominal bandwidth due to data collision resolution and data relaying requirements.
Various potential applications for sensor nodes also present unique challenges. For example, the use of sensor nodes could improve a Health and Usage Monitoring System (HUMS) and/or Condition Based Management (CBM) for one or more components of machinery, such as a helicopter. In this environment, various moving components make attachment and interrogation of the sensor nodes difficult. Additionally, a large amount of vibration may be present, and high speed sampling is often desired. Since many approaches fail to address all of these challenges, current practice requires schedule-based maintenance that includes regular inspections of all of the components of interest and components are often removed and discarded after a period of time and/or amount of usage, often well before the components have approached their true useful lifetime. This situation poses a higher risk of injury to the inspectors/maintenance individuals, and costs billions of dollars annually.
Another potential application is the use of sensor nodes for performing security monitoring. In these applications, multiple possible sensor types (e.g., cameras, microphones, magnetometers, geophones, and/or the like) may be desired. Further, the sensor nodes may need to be capable of covert placement, secure data transmission and storage, and/or independent operation for long periods of time. To date, most approaches use sensors that are wired for power and/or data transmission. Further, human observers/patrols and passive barriers (e.g., fencing) are often utilized due to the limitations of current sensor-based approaches. The continued use of human observers/patrols results in limited monitoring, which also is extremely expensive.
Still another potential application is the use of sensor nodes for performing safety and/or process monitoring (e.g., vehicle monitoring). These applications require a wide range of demands depending on the needs of the particular application. To this extent, numerous different types of sensors may be required and sampling rates may vary from one sample per several minutes to thousands of samples per minute. Current approaches continue to rely on maintenance and posted safety procedures (e.g., vehicle inspections) to avoid unsafe events. To date, some approaches use cameras (e.g., rail crossings, operation areas) and chemical/physical sensors for process monitoring. However, these approaches nearly always use wired sensors. The current approaches rely on individual compliance, which can increase a likelihood of injuries, and result in lost work, production, and operational times.